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x86_64:
o Correct wrong inline assembly in jit_get_cpu.
Previously it could cause data corruption when calling init_jit
if a 64 bit value was stored in %rbx, that was being truncated
in the bad asm.

arm:
o Correct crash in the doc/printf example.
The crash was specific to arm, due to releasing data required
by disassembly in jit_clear_state, before calling jit_disassembly.
o Do not emit a nop stack adjust instruction.

generic:
o Implement the new jit_indirect call.
This call returns a special label, and is required when creating
a label that can be only be reached with jit_jmpr.
o Implement the new jit_set_code interface.
This interface allows telling lightning to write code to a user
provided buffer, instead of lightning mmap'ed and managed memory.
o Implemented the new jit_set_data interface.
This interface allows telling lightning to not use a read only
data buffer for float/double constants, but instead synthesize
the constant; either gpr to fpr move, or gpr to stack and load fpr
from stack.
The interface also allows telling lightning to not generate debug
information, or using an alternate data buffer.

The new generic interfaces are documented and examples provided, in
lightning.info.